1. Field of the Invention
The present invention relates generally to a method for processing an image, and more particularly, to an auto color control method for controlling colors of the image based on a kind of a light source.
2. Description of the Related Art
In general, color temperatures are different according to light source types. The human eye may recognize white colors as the same although adjacent illumination environments, or the light sources, are changed. For example, the human eye may recognize a white color seen under a blue light source or a white light source, such as a fluorescent light, and a white color seen under a red light source, such as an incandescent light, as the same color.
However, since an image sensor is implemented to exactly reproduce a reflected light of a given color temperature, the image sensor cannot actively apply and reflect the color temperature of the light source, and a detected white color is changed as the light source is changed. For example, a white object takes on a red color in the light source having a low color temperature, and the white object takes on a blue color in the light source having a high color temperature. In order to compensate for a color difference generated by the light sources having various color temperatures, most the image processing apparatuses (e.g., digital cameras, digital camcorders, etc.) that include the image sensor perform a digital image processing referred to as an Auto White Balance (AWB).
A method for processing the AWB is implemented by estimating a degree of the color difference by the light source from the image obtained through the image sensor, and determining a color gain for each color of the image sensor in order to compensate for the color difference. Known representative methods for processing the AWB include, a maximum Red-Green-Blue (RGB) scheme of estimating a white color based on a maximum value of an input image, a grayworld scheme of determining an average RGB value of an input color image as a gray color and estimating a reference white color by using the gray color, and a method of estimating the reference white color by using a neural network.